737 engine start-up (white smoke from the base)

[tigger2k8]

was just wondering if anyone can shed light as to what causes the white smoke which happens on the startup from time to time? noticed it a few times recently but mainly on 737s

thanks

ps. not sure if this is the right section or not

[victorc10]

Just unburnt fuel being blown out the tail pipe. If you look right up the pipe (when the engine is not running) you will see little pools of fuel. On start this vaporises into a puff of whitish smoke.

[tigger2k8]

im talking about the base of the engine (not the rear), have noticed the smoke appear just after ignition and continue until the engine is spooled up... have only noticed it in the last few days when the temperature has been in the 20's (*C) for once

[Akrapovic]

White smoke is normally oil related . . . .

[lomapaseo]

Could well be the breather to the oil system as it gets pressurized.

If the engine has worn seal you can even see these puffs long after the engine is running.

[Storminnorm]

Yup, oil system breather pipe.